When it comes to solar panels, real world conditions are often very different those experienced under a standard testing scenario. The manufacturer of REC solar modules says customers using their products are continually yielding higher than expected electricity volumes.
Because solar panel performance varies so much in different locations, environments, weather conditions and even the time of day, manufacturers need a way to assign wattage class; also known as nameplate wattage. The way this figure is arrived at is most often attained under Standard Test Conditions (STC).
STC consists of a solar irradiance of 1,000 W/m², solar spectrum of AM 1.5 and cell temperature of 25°C.
While solar panel brands X, Y and Z may attain near identical performance under standard test conditions and consequently bear the same nameplate wattage, once they are being used in the real world; performance between different brands can vary significantly.
REC reports its award-winning Peak Energy Series solar panels are often exceeding customer expectations and has started formally documenting reports from customers using their modules.
An assessment of one of its own installations at REC’s integrated manufacturing facility in Singapore shows a delivered yield of 5% above that simulated in PVsyst, a solar prediction software application. Singapore is well known for its hot and humid conditions – and heat is the enemy of solar panels as it negatively impacts on performance.
The poorer the quality of a module, the bigger the impact it will usually have on electricity output above cell temperatures of 25°C; a scenario that commonly occurs in countries such as Australia.
While 5% may not sound like a great deal, over the life of a solar panel it represents a substantial amount of electricity in a home solar power scenario and particularly in commercial solar power installations. The array in question was installed in January 2010 and since that time REC has further enhanced its technology.
Earlier this year, REC solar panels were announced the best performing panel of 2011; the result of ongoing independent field testing in real-world conditions of 45 solar module brands.
More recently, REC announced enhancements to its Peak Energy modules, improving yields by up to nearly 6%.
“System designers are increasingly selecting photovoltaic modules based upon yield rather than nameplate watt class. Superior design and manufacturing are at the core of REC’s high-yield performance and reliability,” says the company.